This is an example on how to use R and plotly to draw a 3d function
library(mnormt)
library(plotly)
x <- seq(-3, 3, 0.1)
y <- seq(-3, 3, 0.1)
mu <- c(0, 0)
sigma <- matrix(c(1, 0, 0, 1), nrow=2)
f <- function(x, y) dmnorm(cbind(x, y), mu, sigma)
z <- outer(x, y, f)
plot_ly(z = z, x=x, y=y , type = "surface")